This invention relates to a topical spray preparation for burn treatment and microbial infections on human being or animals. This non-aerosol preparation contains an antimicrobial drug, i.e., silver sulfadiazine, as is dispersed or solubilized in a cream or lotion base matrix which can be sprayed directly from a common trigger spray device. The key component of the matrix can be characterized by it having a suitable molecular weight polymer of cross-linked acrylic acid, such as Carbomers or non-ionic surfactants such as polyoxyethylene alkyl ethers, or any combination of the above materials.
A wound may be defined as a defect or break in the skin that outcomes from physical, mechanical or thermal damage including burns. There are several different types of burns: thermal, chemical, electrical, and those caused by radiation. Deep dermal (second degree) and full thickness (third degree) burns, in which most of the protective epithelium layer and almost all of the element of the skin are destroyed, can rapidly acquire bacteria and cause infection. Infection in the burn wound is the most common management problem in the care of the burn patient. The infection in a major burn could, if untreated, can rapidly develop into a life-threatening septicaemia.
Silver sulfadiazine was first described in 1943 by Wruble (M. Wruble, J. Am. Pharm. Ass. 32, 80, 1943) and was found to be mildly antiseptic. Fox (Ch. L. Fox, Arch. Surg. 96, 184, 1968) rejuvenated the compound for the topical treatment of burns. The 1% w/w of this active drug, in its cream form, has been in clinical use in the U.S.A. since 1973. It is one of only two approved active drugs used as a topical antibacterial agent for adjunctive therapy in second and third degree burns.
U.S. Pat. No. 3,761,590 describes a process for preparing a thick cream ointment containing silver sulfadiazine which is useful in burn treatment. It has been clinically well known that silver sulfadiazine is effective against a wide variety of gram-positive and gram-negative organisms, including Pseudomonas and Candida. However, the activity of the silver sulfadiazine, in the cream form, may be influenced by the following key factors: (1) the release rate of active from the cream matrix in the wound environment; (2) particle size and solubility of the active drug in the fluids of the wound bed; and (3) stability of the active in the cream matrix. In addition, the cream product contains poor water soluble fat and oil materials, making it mandatory that the treated area must be cleaned and the cream must be removed from the wounded area, which is time consuming and excruciatingly painful.
Presently, these cream base products can only be applied using only sterile techniques. Again, the task of this kind of drug administration is extremely time consuming and can allow for potential cross-contamination between patients due to the multiple use of the same container. The latter reason usually restrains the practitioner to prescribe this product to the patient, and to be used only in the clinical setting, not at home after each treatment. Therefore, the patient has to return to the burn center for a new application of the cream, even if the burn is minor. Accordingly, there is a definite desperate need in the art for developing an economical, less painful, easy to apply, clean, and cross-contamination free formulation for a burn and antibacterial treatment.
U.S. Pat. No. 5,143,717 presents a specific aerosol formulation of an antibiotic including silver sulfadiazine in a cream base as a topical water soluble foam. This invention provides several advantageous features over the presently marketed formulations while minimizing the disadvantages thereof. However, there are four key points related to this invention that need to be clarified: (1) The manufacturing process requires special equipment for product aerosolization. (2) This aerosol product requires the interior of an aerosol can to be lined or have a protective coating in order to stabilize the active silver compound. (3) The possible chilling effect on the sensitive wound area may impact the patient when sprayed. (4) The foam, when in contact with the patient, does not adhere to the wound area and it easily slides off, and the concentration of the antimicrobial agent at that location of treatment is diminished, and the addition of dressings are unable to properly cover and hold the antimicrobial foam in place. The currently marketed product instructions require the patient to have total coverage and contact of the product with the damaged site at all times.
U.S. Pat. No. 4,803,066 teaches a topical preparation comprises a synergistic mixture of an antimicrobial silver compound and an antimicrobial azole compound in hydrophilic and hydrophobic ointment, tablet, pessary and aqueous gel. This invention describes a number of suitable gelling agents including polyoxyethylene-polyoxypropylene diol block copolymers (poloxamer) and no technology about the aqueous gel for trigger spray has been mentioned.
This block copolymers are known as gelling agents for a substantial amount of time. U.S. Pat. No. 3,639,575 accomplishes the invention by the use of certain polyoxyethylene polyoxypropylene block copolymers (poloxamer) as a matrix for silver ions in the preparation of aqueous gel compositions.
U.S. Pat. No. 4,551,139 discloses an apparatus and method for spray application of a silver sulfadiazine cream to treat the burn. The cream is pushed toward an outlet in a collapsible bag, in which the cream is disposed by means of pressure applied to the exterior surface of the bag, and conveying the cream from the outlet to a sanitary spray nozzle by means of a compressed air operated sanitary pump. This is a complex system in terms of the manufacturing process and practical clinical application. This invention did not reveal the formulation of the specific high viscosity cream.